The present invention relates to video processing architectures, and more particularly to an architecture for multi-format video processing of both high definition television (HDTV) signals and standard definition television (SDTV) signals.
Manipulation of a color video signal generally requires processing of three components, such as one luminance signal and two color difference signals. The two color difference signals usually have half the bandwidth, and in digital systems half the sampling rate, of the luminance signal. In digital processing systems such processing is often called 4:2:2 where the ratio of the numbers indicates the relative bandwidth of the difference signalsxe2x80x94luminance (full bandwidth): chrominance 1 (half bandwidth):chrominance 2 (half bandwidth). The digital color difference signals may be referred to as CB and CR.
Current state of the art makes use of this relationship by using two processing paths instead of three. One path carries the full bandwidth luminance component signal, while the other carries the half bandwidth color difference component signals in an interleaved fashion. The two processing paths have the same total sampling rate. For SDTV according to the ITU-R 601 standard luminance component signal processing is performed at 13.5 MHz. Since each color difference component signal is sampled at 6.75 MHz, the interleaved color difference signal also has a total sample rate of 13.5 MHz. For HDTV systems, as characterized by SMPTE standards 274M and 296M, the luminance component signal is sampled at 74.25 MHz and the two color difference component signals are each sampled at 37.125 MHz. Current equipment, as shown in FIG. 1, uses two processing paths, each operating at 75.25 MHz.
To provide cost-effective products it is important that one design be used for as many applications as possible, and it is desirable to offer products that use the same design for both SDTV and HDTV processing. It is possible to process SDTV in an HDTV device, but high-speed processing is usually more expensive and this may not be an economical solution.
What is desired is a device that is able to process both SDTV and HDTV signals in an economical manner.
Accordingly the present invention provides an architecture for multiformat video processing that handles either standard definition television (SDTV) signals or high definition television (HDTV) signals. The luminance component signal of the HDTV signal is processed along one path and the interleaved color difference component signals are processed along a second path. For SDTV only one of the paths is used and, in a unit intended for SDTV only, only one path need be installed. The luminance and color difference component signals are interleaved and optionally stuffed with filler bits to produce an interleaved signal at or below the HDTV data rate. After processing the interleaved signal, the processed component signals are deinterleaved to recover the processed SDTV signal. The color difference component signals may be upsampled prior to interleaving to the same bandwidth as the luminance component signal to simplify control signals generation, and then filtered and subsampled after deinterleaving to recover the processed SDTV signal.
The objects, advantages and other novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.